Dynamic 31P MRS was performed during a standardized exercise of the lower leg, in patients with chronic fatigue enrolled in 2 clinical studies: multiple sclerosis patients and COVID19 patients that were hospitalized in intensive care unit and requiring respiratory assistance. In this work, we also revisit certain assumptions on the metabolite T1 and question shortcuts often made to shorten 31P protocol for a better patient’s compliance.

Lower leg resting-state BOLD images (n=8 males, 4 endurance, 4 power athletes), were acquired after 30min of rest, allowing for blood-flow normalization. BOLD images were motion corrected and the gastrocnemius and soleus manually segmented using an anatomical reference for their differing twitch fibre profiles. Voxel-wise BOLD mono- and bi-fractal dimension were computed using the scaled windowed variance approach, with linear detrending, removing scanner induced low-frequency variations. The bi-fractal dimension was significantly different between endurance and power groups in both muscles. Specific bi-fractal components more readily distinguished soleus and gastrocnemius for the endurance (I) and power (II) group, when at rest.

Diabetic peripheral neuropathy (DPN) is characterized by increased adiposity implicated in metabolic dysfunction. Proton-based Dixon MRI is an appropriate means to quantify adiposity, but analysis requires time-consuming manual image segmentation. To address this problem, we developed an automated segmentation algorithm based on convolutional neural networks that provided high dice similarity coefficient scores (>0.88) on multiple regions of interest (ROI) within the calf. We utilized the networks to analyze fat fraction trends in individuals with DPN following a 10-week supervised exercise program. We measured decreased adiposity in the combined calf interstitial and muscle space (P<0.1) but not in individual muscle ROIs.

ACL T2* metrics were evaluated over the course of the menstrual cycle. During the pre-ovulatory phase, normally ovulating case subjects exhibited significantly shortened mean and median T2*S metrics compared to the post-ovulatory phase. Anovulatory control subjects displayed no significant changes in any ACL T2* metrics over time. Findings suggest that an increase in collagen bound water (T2*S) is present within the ACL during the pre-ovulatory phase, when both ACL-injury risk and anterior knee laxity are also increased.

The meniscal-extrusion may disturb the stability of the knee-joint, and depicts laxity in the meniscal-hoops. The degraded meniscal site usually show changes  in the MR images (T1, T2, and Proton-Density-weighted images). However, the laxity of a specific meniscal segment and its effect on adjacent segment’s deformation is unknown. The current study attempt to address this problem using MRI data (with and without loading) and a finite-element-model. Each meniscal-hoop’s (lateral and medial) lengths, thickness, and meniscus-extrusion was measured to evaluate load-bearing changes. Medial meniscus hoop’s Anterior-meniscal-length(ML), Posterior-ML, Central-ML, and meniscus-extrusion show substantial change(>5%) during load. 

Aponeuroses play a crucial role in the transmission of mechanical load in the muscle-tendon unit. Their contribution is, however, still under debate and they are difficult to image with MRI due to their short T₂^* decay. In this work, we use high-resolution 3D ultra-short echo time imaging with 50 echoes to investigate the T₂^* decay of the aponeurosis and build a three-component model to quantify the T₂^* values. Additionally, we quantified T₁ using variable flip angle imaging. To our knowledge, this work is the first to report T₁ and T₂^* values of the aponeurosis.

Knee articular cartilage thickness may potentially serve as a marker for monitoring of the knee cartilage status. However, it is challenging to measure and quantify the articular cartilage thickness using in vivo MRI. In the present study, we evaluated 6 unpaired lower extremies of body donors using both a prototype segmentation software and a semi-automatic approach. Our results showed a low correlation (r = 0.45) between the two methods, indicating the challenge of determining cartilage thickness from MR images.

Knee osteoarthritis results from inflammatory, mechanical, and metabolic processes, leading to chronic degenerative changes. The purpose of this study was to investigate the cross-sectional associations between thigh muscle volume or intermuscular fat volume, and relative muscle sizes, from T1-weighted MR images of 100 thighs, and radiographic knee osteoarthritis (ROA) using Kellgren-Lawrence grades. The results showed that lower volumes of the quadriceps and the anterior muscle compartment of the thigh relative to total muscle volume, as well as relative higher hamstring muscle volume were associated with presence of ROA (P<0.05).

In this study we evaluate the viability of using ZTE, a novel MRI sequence for bone imaging, with deep-learning (DL) reconstruction to assess glenohumeral shoulder instability, aiming to improve signal-to-noise ratio (SNR) and get comparable images to CT, the gold standard technique for surgical planning. Bone loss measurements were performed on both techniques achieving almost perfect inter-modality agreement on 20 patients. This approach could prevent the patient from receiving ionizing radiation concomitant to CT examination and could be combined in a single routine shoulder examination with other MR sequences for a complete study and optimized patient workflow.

Elbow MRI contributes essential information in acute and chronic elbow injuries. Elbow MRI is ideally obtained in the superman position (prone position with elbow extended, arm elevated above the head, and hand pronated); however, this position can be challenging for patients due to injury-related pain and positioning-related discomfort. To shorten the exam time and reduce patient discomfort, we developed a 4-fold accelerated 5-sequence 6-minute clinical MRI protocol using combined simultaneous multi-slice and parallel imaging acceleration of turbo spin echo sequences. In this study, we compared the image quality of our conventional and novel accelerated elbow MRI protocols.

This study aims to evaluate cartilage degeneration using 3D UTE-Cones-AdiabT_1r imaging at 3T. In total 66 human subjects were recruited. KL and WORMS were evaluated by two MSK radiologists. The performance in evaluating cartilage degeneration was assessed via Spearman’s correlation coefficient and the area under the curve (AUC) calculated according to the receiver-operating characteristic (ROC) curve. Higher UTE-Cones-AdiabT_1r values were observed in larger and deeper cartilage lesions. The diagnostic threshold of UTE-Cones-AdiabT_1r for mild cartilage degeneration was 39.4 ms with 80.8% sensitivity and 63.5% specificity. The AUC value for mild cartilage degeneration (WORMS=1) was 0.8 according to the ROC curves.

We implemented and compared three different reconstructions for 3D T₂ mapping of the knee: I) a standard image reconstruction followed by an analytical fit, II) a standard image reconstruction followed by a dictionary fit, and III) a denoised image reconstruction followed by a dictionary fit. We optimized and compared these techniques in phantoms, five healthy volunteers, and five patients with mild osteoarthritis. The third reconstruction resulted in the highest accuracy and precision while retaining the spatial resolution, and allowed the load-bearing cartilage in the mild-OA patients to be differentiated from that in the healthy volunteers.

The overall goal of this work is to apply multi-nuclear sodium MRI to evaluate the therapeutic effect of physical therapy in women with lipedema.  Lipedema is a fat disorder affecting approximately 11% of women and since it is largely refractory to diet and exercise, objective measures of condition severity and treatment response are required. We applied sodium MRI to evaluate whether abnormal tissue sodium accumulation in the legs, a previously established lipedema biomarker, reduced following physical therapy in persons with lipedema. Results show reduction of skin and subcutaneous sodium, which corresponds with reduced pain and increased function.  

An efficient sequence to acquire sodium image, i.e., rotation of the spiral disc, was developed last year. This sequence is further developed to separate the sodium signal into intra- and extra-cellular sodium by collecting multiple echoes and bi-exponential curve fitting. This method is confirmed on agarose phantom for T2* mapping and on human lower-leg muscle with an isometric plantar flexion exercise for separation of intra- and extra-cellular sodium. In the calf muscle experiment, it was found that the intracellular sodium was increased more than the extra-cellular sodium. This method finally allows studying separately the intra- and extra-cellular sodium in muscles.

The majority of studies investigating changes in skeletal muscle parameters with MRI have focused on analyzing the effects before and after exercise training. In this work, we analyze the effects of regular repetitive training on low back muscle by determining T₁ and T₂ parameters in three cohorts of subjects characterized by different levels of physical activity.

An assessment of image quality is presented from a multicentre WB-MRI study. A radiologist assessed image quality and the presence/severity of several common artefacts/image quality issues and metrics were also defined to measure these quantitatively. Image quality was consistently good or excellent, with only one DWI examination deemed non-diagnostic. In the case of most artefacts, the quantitative measurements were found to correlate with radiological assessment and a statistically significant ordinal regression model was found to predict DW image quality score using the quantitative measurements. These measurements could form part of an automated quality control pipeline for multi-centre WB-MRI studies.